Research On The Mechanical Behavior Of Underpass Tunnel And Existing Tunnel

With the rapid development of society,increasing the use of urban underground space is the only way to alleviate the problem of urban ground space occupation.The development of underground space can effectively alleviate traffic pressure,but at the same time it also brings about the intersection of underground structures.Because the perfect underground transportation system is not built all at once,the subsequent construction will definitely affect the mechanical behavior of the existing structure.The clearance,crossing angle and diameter changes between the newly built structure and the existing structure will affect the structure.Produces different changes in mechanical properties,so this article mainly studies and analyzes the changes in the mechanical behavior of the underpass tunnel and the existing tunnel.The tunnel-soil three-dimensional model is established by ABAQUS,and the following analysis is carried out through simulation:(1)Research on the mechanical behavior of the underpass tunnel and the existing tunnel under the same soil layer.Analyze the underpass tunnel and the existing tunnel in the same soil layer,the underpass tunnel and the existing tunnel are orthogonal,change the distance between the underpass tunnel and the existing tunnel,and analyze the changes in the mechanical behavior of the underpass tunnel and the existing tunnel,To determine the distance between the underpass tunnel and the existing tunnel with greater mutual influence.When changing the tunnel spacing,the impact on the existing tunnel is greater than that of the underpass.The minimum safe distance between the underpass and the existing tunnel is1.05 D.(2)In the case of different diameters of the underpass tunnel,the mechanical behavior of the underpass tunnel and the existing tunnel is studied.Analyze the changes in the mechanical behavior of the underpass tunnel and the existing tunnel when the underpass tunnel is at the same diameter but the distance between the underpass tunnel and the existing tunnel is changed;analyze the underpass tunnel at the same distance but with different underpass tunnel diameters,The mechanical behavior of the tunnel and the existing tunnel are changed,and the minimum safe distance between tunnels under different tunnel diameters is obtained.The larger the diameter of the underpass tunnel,the greater the impact on the existing tunnel.When the underpass tunnel has a diameter of 4m,the minimum safe distance between the underpass tunnel and the existing tunnel is 0.75 D.When the underpass tunnel is 6m apart,the underpass tunnel The minimum safe distance from the existing tunnel is 0.87 D.When the distance between the underpass tunnel is 8m,the minimum safe distance between the underpass tunnel and the existing tunnel is 1.05 D,when the underpass tunnel is 10 m apart,the underpass tunnel and the existing tunnel The minimum safety distance is 1.23 D.(3)Under the condition that the crossing angle of the underpass tunnel and the existing tunnel is different,the mechanical behavior of the underpass tunnel and the existing tunnel is studied.Analyze the changes in the mechanical behavior of the underpass tunnel and the existing tunnel under the same crossing angle with the existing tunnel but at different intervals;divide the underpass tunnel and the existing tunnel at the same crossing angle when the underpass tunnel and the existing tunnel are at different intervals The mechanical behavior of the underpass tunnel and the existing tunnel is studied,and the minimum safe distance between the underpass tunnel and the existing tunnel under different conditions and the displacement stress change law of the tunnel are obtained by analysis.It shows that the larger the diameter of the underpass tunnel,the greater the impact on the existing tunnel.When the crossing angle of the tunnel is 30°,the minimum safe distance between the underpass tunnel and the existing tunnel is 1.29 D,and when the crossing angle of the tunnel is 45° When the minimum safety distance between the underpass tunnel and the existing tunnel is 1.25 D,when the intersection angle of the tunnel is 60 °,the minimum safety distance between the underpass tunnel and the existing tunnel is 1.18 D,and when the intersection angle of the tunnel is 90° At the time,the minimum safe distance between the underpass tunnel and the existing tunnel is 1.05 D.